Phenols labeled

Procedures for shipping boric acid esters depend on the particular compound. Aryl borates produce phenols when in contact with water and are therefore subject to shipping regulations governing such materials and must carry a Corrosive Chemical label. Lower alkyl borates are flammable, flash points of methyl, ethyl, and butyl borates are 0, 32, and 94°C, respectively, and must be stored in approved areas. Other compounds are not hazardous, and may be shipped or stored in any convenient manner. Because borate esters are susceptible to hydrolysis, the more sensitive compounds should be stored and transferred in an inert atmosphere, such as nitrogen. 

Isotope labeling by derivative formation with deuterated reagents is useful for the preparation of analogs such as dg-acetonides, da-acetates, da-methyl ethers, dg-methyl esters, etc. The required reagents are either commercially available or can be easily prepared. (The preparation of da-methyl iodide is described in section IX-F. Various procedures are reported in the literature for the preparation of dg-acetone, da-diazometh-ane57.i63.i73 and da-acetyl chloride. ) These reactions can be carried out under the usual conditions and they need no further discussion. A convenient procedure has been reported for the da-methylation of sterically hindered or hydrogen bonded phenolic hydroxyl functions by using da-methyl iodide and sodium hydroxide in dimethyl sulfoxide solution. This procedure should be equally applicable to the preparation of estradiol da-methyl ether derivatives. 

Olefin diacylation with carbonjd-labelled acid derivatives is ai excellent method for obtaining O-labeled pyrylium salts (194) and hence, ring-labeled aromatic compounds such as pyridines ana phenols. 

For example, all three isomeric aryl acetates (1) undergo bromo- and iododesilylation, providing a route (6) to radio-halogen-labelled phenols the free phenols and methyl ethers corresponding to (1) proved too reactive, giving products of both substitution and desilylation. 

Instead of immobilizing the antibody onto the transducer, it is possible to use a bare (amperometric or potentiometric) electrode for probing enzyme immunoassay reactions (42). In this case, the content of the immunoassay reaction vessel is injected to an appropriate flow system containing an electrochemical detector, or the electrode can be inserted into the reaction vessel. Remarkably low (femtomolar) detection limits have been reported in connection with the use of the alkaline phosphatase label (43,44). This enzyme catalyzes the hydrolysis of phosphate esters to liberate easily oxidizable phenolic products. 

Table VIII. Quenching Effects by Oxalates and Product Phenols on CBI- and Dansyl-Labeled Amino Acids...

During fermentation, the betacyanins turned out to be more stable than the betaxanthins, which is assumed to be due to their thermal stability rather than different tendencies of pigments toward microbial degradation. Besides these biological tools, beet extracts may also be purified by column chromatographic techniques. After removal of sugars, salts, and phenolics, the nature-derived color preparation will, however, require E number labeling. ... 

The uptake and biotransformation of benzene from soil and the atmosphere has been studied in a nnmber of plants. It was shown that in leaves of spinach Spinacia oleraced) the label in -benzene was fonnd in mnconic, fnmaric, snccinic, malic, and oxalic acids, as well as in specific amino acids, and that an enzyme preparation in the presence of NADH or NADPH prodnced phenol (Ugrekhelidze et al. 1997). 

A site at the Agricultural Experimental Station (Ithaca, NY) was treated in microcosms with C-labeled glucose, phenol, caffeine, and naphthalene. Levels of C02 were measured to assess utilization of the substrates, and the populations analyzed by separating the C-labeled DNA by density centrifugation, followed by PCR amplification and sequencing of 16S rRNA (Padmanabhan et al. 2003). Populations contained relatives to a range of bacteria that varied with the substrate. Only relatives of Acinetobacter were found in all samples, and for caffeine only Pantoea. 

A phenol-degrading community was examined using phenol followed by analysis of the stable-isotope-labeled RNA by equilibrium density centrifugation, and complemented... 

A sandwich electrochemical enzyme immunoassay has been described for IgG Alkaline phosphatase was again used as the enzyme label with the conversion of phenyl phosphate to phenol being determined electrochemically by LCEC. A detection limit of 10 pg/mL was reported. 

Examples of PLC with autoradiography detection include the published studies on labeling of l- H-PAF-aceter [25] diazinon and related compounds from plant material [26] metabolic fate of triamcinolone acetonide in laboratory animals [27] synthesis of 4-S-cysteaminyl-[U- " C]phenol antimelanoma agent [28] radiolabeled... 

At this point, the anaiyte may not be amenabie to UV, FL, or EC detection. In this case, the best course of action may be to choose LC/MS (see Section 4.2). However, one other option is to use a pre- " or post-coiumn derivatization step to increase the detectabiiity of the anaiyte with respect to FL or UV. Fluorescent or UV labels are available for carboxylic acids," amines, phenols, and thiols. The decision to use pre- or post-column derivatization is predicated upon the functionality of the analyte available for derivatization and the rate and extent of the reaction between each derivatizing agent and the analyte. 

C12 to C20, primarily Ci6 to ( is), used as surface lubricants in the manufacture of food-contact articles. The method, which uses ethyl palmitate (Eastman Chemicals No. 1575 Red Label) as an internal standard, has been validated at 200 ppm total FAME [185]. Other FAME standards (methyl palmitate, methyl stearate, methyl oleate, methyl linoleate and methyl linolenate) are available (Applied Science Laboratories) [116], Worked out examples of additive determinations are given in the Food Additives Analytical Manual [116], which also describes a great many of indirect food additives, such as BHA, BHT, TBHQ, l-chloro-2-propanol, DLTDP, fatty acid methyl esters, w-heptyl-p-hydroxybenzoate, propyl-gallate, sodium benzoate, sodium stearoyl-2-lactylate, sorbitol and phenolic antioxidants. EPA methods 606 and 8060 describe the CGC separation of phthalate esters (direct injection) (cf. Figure 4.2). 

Since the imidazolide method proceeds almost quantitatively, it has been used for the synthesis of isotopically labeled esters (see also Section 3.2), and it is always useful for the esterification of sensitive carboxylic acids, alcohols, and phenols under mild conditions. This advantage has been utilized in biochemistry for the study of transacylating enzymes. A number of enzymatic transacylations (e.g., those catalyzed by oc-chymo-trypsin) have been shown to proceed in two steps an acyl group is first transferred from the substrate to the enzyme to form an acyl enzyme, which is then deacylated in a second step. In this context it has been shown[21] that oc-chymotrypsin is rapidly and quantitatively acylated by Af-fraw.s-cinnamoylimidazole to give /ra/w-cinnamoyl-a-chymotrypsin, which can be isolated in preparative quantities and retains its enzymatic activity (see also Chapter 6). 

We have studied demulsifier association by the electron spin resonance (ESR) technique. The spin label is covalently attached (Figure 5a) to the demulsifier. Normally, the ESR spectrum of a freely tumbling nitroxyl radical consists of three sharp peaks (Figure 5b). However, the spectrum for a tagged ethoxylated nonyl phenol resin (Figure 6a or 6b) shows only a single broad peak. 

The dienone intermediate (53a), as well as enolising to the phenol (52a), is itself capable of undergoing a Cope rearrangement to yield a second dienone (cf. 56a), whose enol is the p-substituted phenol (c/ 57a). Enolisation normally predominates, but where (51) has o-substituents, i.e. (54a), o-enolisation cannot take place, and only the p-phenol (57a) is then obtained. That this product is indeed formed not by direct migration of the allyl group, but by two successive shifts, is suggested by the double inversion of the position of the, 4C label in the allyl group that is found to occur ... 

Chemical attachment of a detectable component to an oligonucleotide forms the basis for constructing a sensitive hybridization reagent. Unfortunately, the methods developed to crosslink or label other biological molecules such as proteins do not always apply to nucleic acids. The major reactive sites on proteins involve primary amines, sulfhydryls, carboxylates, or phenolates— groups that are relatively easy to derivatize. RNA and DNA contain none of these functionalities. 

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